Fuels most commonly utilized in automobiles and trucks in the United States and other nations of the world are gasoline and diesel which are customarily dispensed directly into vehicle fuel tanks at motor vehicle fueling stations. Such fuel is usually dispensed from an underground storage tank where it is stored in large volumes. A submersible pump extending into or communicating with the storage tank pumps fuel to the aboveground fueling station. The typical fueling station includes one or more metering systems each with a flexible hose and nozzle. Solid contaminants, such as dirt, rust, and the like, have always been a problem when it occurs in vehicle fuel. Water has also been a constant problem in fuels. The problem with particulate and water contaminants is much more serious at the present time than in the past because of the almost universal adoption of fuel injection systems for vehicle engines. Fuel injection systems are considerably more sensitive to particulate matter than earlier type carbureted fuel systems. While diesel engines have always employed fuel injectors, in recent years the use of fuel injectors for gasoline engines has become common.
Distributors of gasoline and diesel fuels have in recent years given increased attention to the requirements of clean fuel. Water is a continuous problem in connection with fuel since tanks, pipelines and so forth in which fuel is stored and/or transported are subject to condensation. Condensation is substantially impossible to prevent and therefore accumulation of some water in stored fuel is inevitable. Water from spill containment manholes at fill risers is also a source of fuel contamination.
In order to combat the possibility of water and/or particulate contaminants from passing into a vehicle fuel tank, fueling stations have employed the use of small canister type filters. These canister type filters are designed to absorb water passing therethrough and intercept contaminants. In order to prevent water from being dispensed with gasoline or diesel fuel, canister filters have been devised that include an internal valve arrangement that closes off when the filter has absorbed a predetermined amount of water. For reference to a filter that functions to shut off in the event of water contamination, see U.S. Pat. No. 4,485,011, issued Nov. 27, 1984, entitled "Fuel Containment Monitor With A Shutoff Valve." This prior issued patent shows the use of a ball functioning as a valve which is moved to a closed position when the pressure drop across a filter element reaches a preselected level due to the absorption of water by the filter element. The ball moves against a seat to prevent further fuel flow through the filter.
An improved canister type filter for closing against fuel flow when a predetermined amount of water has been absorbed by the filter having a valve which, after having moved to the valve closed position, is retained in such position is disclosed in U.S. Pat. No. 4,959,141 entitled "Fuel Filter With Positive Water Shutoff" issued Sep. 25, 1990.
While these water absorbing and flow terminating filter elements have been successful in achieving their intended results of closing against further fuel flow in the event of the absorption of predetermined amounts of water, the application of such filters has been limited since they have typically been employed as canister filters attached aboveground to fuel dispensing units, and such aboveground applications are potentially environmentally contaminating. Therefore, the present disclosure is directed to a liquid fuel dispensing system having means for preventing inadvertent water and particulate contamination which overcomes the problems and limitations with the existing systems as used in service stations today. Particularly, the disclosure herein provides a fuel dispensing system including an underground sump arrangement for receiving a filtration vessel therein and in which the filtration vessel is of a size permitting the use of relatively large filter elements. Larger filter elements require less frequent replacement, thus reducing the atmospheric and ground water contamination that occurs with more frequent replacement of small filter elements attached aboveground directly to fuel dispensing units. Further, the disclosure herein provides an improved integrated filtration unit for use in an overall system of fuel dispensing wherein the pump for pumping the fuel from an underground storage tank to a motor vehicle fueling station and all required filtration to intercept particulate matter and water are achieved within a confined underground sump, the integrated filtration unit being attached to a riser pipe extending upwardly from a fuel storage tank.
This disclosure is related in subject matter to application Ser. No. 07/640,139 filed Jan. 11, 1991, now U.S. Pat. No. 5,122,264, entitled "Liquid Fuel Dispensing System With Improved Means Of Preventing Contamination", Kirby S. Mohr and Thomas F. Wilson, Applicants. The description and drawings of U.S. Pat. No. 5,122,264 are incorporated herein by reference.